A pattern evaluation method for evaluating a mask pattern includes generating desired wafer pattern data corresponding to the evaluation position of a mask pattern, generating mask pattern contour data based on an image of the mask pattern, and performing a lithography/simulation process based on the mask pattern contour data and generating predicted wafer pattern data when the mask pattern is transferred to a wafer. Further, it includes deriving positional offset between the mask pattern contour data and mask pattern data, correcting a positional error between the desired wafer pattern data and the predicted wafer pattern data based on the positional offset, and comparing the desired wafer pattern data with the predicted wafer pattern data with the positional error corrected.